Whole Transcriptome Sequencing of Capsicum chinense King Chilli from Manipur for identification of genes related to capsaicinoids and carotenoids
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ABSTRACT: Whole Transcriptome Sequencing of King Chilli from Manipur for identification of genes involved in biosynthesis of capsaicinoids and carotenoids
Project description:The Capsicum genus shows remarkable phenotypic diversity, making it an excellent system to study non-climacteric fruit ripening. Unlike climacteric model species, such as tomato (Solanum lycopersicum), the regulatory networks linking transcriptome and metabolome to fruit quality traits remain poorly understood in non-climacteric crop species. To address this gap, we selected four contrasting C. chinense accessions and performed integrated transcriptomic and metabolomic analyses to investigate the regulation of total soluble solids (TSS) accumulation. We profiled 16,922 genes and 63 metabolic features across two fruit developmental stages (immature and mature), including sugars, organic acids, capsaicinoids, and other secondary metabolites. We identified more than 3,800 differentially expressed genes and detected strong correlations between gene expression and metabolite levels. Some metabolites, including chlorophylls, carotenoids, and starch, showed consistent temporal trends across genotypes, while others showed genotype-dependent variation. Our results demonstrate that pepper fruit ripening involves a transcriptional shift toward soluble sugar accumulation, characterized by upregulation of starch-hydrolyzing enzymes (CaAMY1/2, CaBAM1), invertases (CaINV1, CaCWINV3), sucrose synthase (CaSUS2), and the sugar transporter CaSWEET10, alongside downregulation of the starch biosynthetic gene CaSBE1. Among these, CaSUS2, CaSWEET10 and CaBAM1 emerged as key candidate regulators. These results suggest that coordinated starch degradation and sucrose transport primarily drive TSS increase, while secondary metabolism undergoes substantial changes during ripening but does not appear to be a major contributor to this process.
Project description:Capsicum frutescens is one of the chilli varieties, with erect, highly pungent fruits. This variety is used to prepare hot sauces, chilli concentrates, and oleoresin. Its fruits are also used in traditional Indian medicine to treat arthritis and zoster related pain management. Infection by Polyphagotarsonemus latus commonly called as the Broad mite in chilli, make the leaves turn coppery and dark, show symptoms of leaf curl and stunted growth that eventually results in low yield and economic loss. We carried out gel-free, labelled mass spectrometry-based quantitative proteomic analysis of leaves and apical meristems of healthy and infected plants. We identified a total of 5799 proteins, of which total of which, 1677 proteins found to dysregulated in infested plants.
Project description:Chromoplasts are typical plastids of fruits and flowers, deriving from chloroplasts through complex processes of re-organisation and recycling. Since this transition leads to the production of reactive species, chromoplasts are characteristic sites for biosynthesis and accumulation of carotenoids and other antioxidants. Here, we have analysed the chromoplast membranes from Capsicum annuum L. fruits, finding a significant expression of the capsanthin/capsorubin synthase. This enzyme was isolated by a very mild procedure allowing its analyses under quasi-native conditions. The isolated complex appeared as a red coloured homo-trimer, suggesting the retention of at least one of the typical carotenoids from C. annuum. Moreover, the protein complex was co-purified with a non-proteinaceous fraction of carotenoid aggregates carrying a high molecular weight and separable only by Size Exclusion Chromatography. This last finding suggested a relationship between the carotenoids synthesis on chromoplast membranes and the presence of organised carotenoids aggregates typical for chromoplasts. Further MS analyses also provided important hints on the interactome network associated to the capsanthin/capsorubin synthase, confirming its functional relevance during ripening. Results are discussed in the frame of the primary role played by carotenoids in quenching the growing oxidative stress during fruits ripening.